Is inflow's fluid subject to gravity?
Quick answer: Yes it does.

I set up a simple scene to test this.  Cube scaled up be 10, set as the Fluid Domain.  Added cylinder set as Fluid Inflow.  I then baked, and it dripped out of the cylinder, landing on the bottom of the domain.

If you would like, here is a .blend file with my test scene, however you may need to bake the fluid sim again (should take about a minute):